Process for the continuous manufacture of crimped threads or fibres of polymeric epsilon-caprolactam



Jan. 26, 1960 KUNZ r 2,922,196

PROCESS FOR THE; CONTINUOUS MANUFACTURE OF CRIMPED THREADS 0R FIBRES OF POLYMERIC E-CAPROLACTAM Filed March 15, 1954 Kuduzvemo s M EGZEF HAFNER M5 MAQE ATTORNEYS United States Patent PROCESS FOR THE CONTINUOUS MANUFAC- TURE OF CRllVIPED THREADS OR FIBRES OF POLYMERIC e-CAPROLACTAM Application March 15, 1954, Serial No. 416,319

Claims priority, application Germany March 16, 1953 4 Claims. (Cl. 19-66) This invention relates to a process for the continuous manufacture of crimped threads or fibres of polymeric e-caprolactam.

Various methods have been used for the preparation of crimped threads or fibres of linear polyamides. It has been found, however, that in many cases the properties of the crimped threads or fibres prepared in known manner do not meet the requirements of the consumer since the crimp effect cannot be varied sufficiently and cannot be adapted to changing requirements. This applies, above all, when the process is to be carried out continuously for reasons of economy and uniformity.

For certain purposes, especially for the manufacture of yarns having a full hand, fibres are needed which have an especially marked crimp stability. Furthermore, there is often required a crimping similar to that of merino wool, which is a wool of high quality.

Now, we have found that crimped threads or fibres of polymeric e-caprolactam, the crimping of which corresponds to a pronounced merino crimping, can be obtained when, by a continuous method, a large number ofsingle fibers, that is to say, a tow of continuous fibers, in a lactam-containing state in which monomeric or low polymeric e-caprolactam may also be present, is stretched and mechanically crimped, and washed with hot Water at about 80 C. to about 100 C. without tension in order to remove the low molecular portion, subsequently dried, and finally cut if so desired.

The polymeric e-caprolactam contains more than 6 percent advantageously about 7 to about 15 percent of monomers or low polymers.

The stretching process may be carried out in several stages either in the cold-at about room temperatureor also at a progressively increasing temperaturefrom about room temperature to 200 C. The tow may also be heated after the cold stretching process and before a new stretching process, under tensile stress, to temperatures above 50 C., advantageously to temperatures ranging between 140 C. and 170 C. In addition, according to the invention, the tow stretched in the cold may be after-stretched in an atmosphere of steam, advantageously at temperatures between 90 C. and 105 C., whereby a very desirable reduction of the elongation at break and an increase of the stability of the finished fibre is effected. The tow is crimped mechanically, this being preferably carried out in a compression crimping apparatus that may be heatable. In order to remove the low molecular coustituents, the crimped tow is treated without tension with water at a temperature above 80 C. as described above. Besides the removal of the monomeric and low polymeric constituents from the tow, this washing process effects a fixation of the crimping and also increases the crimp stability.

When the crimping is effected by the usual mechanical means, for example, a heated pair of gear wheels, the stability of a polyamide fibre amounts to about 45 percent, while the crimp stability of the fibre made according to the process of the present invention amounts to ice about 60-70 percent. This increase of the crimp stability is particularly favourable in processing the fibres, and especially in scribbling, carding, and combing them, so that yarns are obtained which, with regard to uniformity and full hand, are equal to the best woolen yarns. The crimp stability percentage is determined in the following manner: The fiber is fixed between two clamps, the distance between them being L and charged with a weight corresponding to the weight of 18 meters of the fiber. When charged with this weight the fiber does not lose its crimping. The crimping is then removed by slowly moving-the lower one of the clamps downward until the fiber is smooth. The distance between the two clamps is designated as L The crimping degree K which corresponds to the so-called initial crimping degree of Examples 1 and 2 is then The lower one of the clamps is then removed and the fiber is charged for one minute with a weight corresponding to the weight of 5,000 meters of the fiber. The charge is then completely taken away from the fiber for one minute.

The crimping degree is again measured on this fiber in the same manner as described above. From these measurements the value of K (crimping degree after continuous tensile stress) is obtained.

The crimp stability in percentage (B) may be calculated according to the formula After washing the tow without tension, the main portion of the water is squeezed out. The tow is then prepared, if desired, and finally dried without tension. The drying without tension is carried out in known manner by laying the tow in loops on a. belt drier. If desired, the tow may be cut after drying.

An apparatus for carrying out the process of this invention is illustrated in section in the accompanying drawing.

Referring to the drawing, the device for washing the mechanically crimped tow, consists generally, of a tank 1, in which a container 2 is vertically inserted. The container 2 tapers towards its lower end and is perforated as a sieve, and has at its lower end an opening 3 large enough to allow the tow to pass through. Furthermore, the said apparatus comprises a turner bar 4, draw-in rollers 5, draw-0E rollers 6, and a known means (not shown), for the regular laying down of the tow in the container 2. Water 8 circulates through tank 1, passing through container 2.

The following examples serve to illustrate the invention but they are not intended to limit it thereto:

Example 1 A newly spun tow of polymeric ecaprolactam containing, besides diand trimeric lactam, also about 7 percent of monomeric lactam, and having an individual count of 11 denier and a total count of 300,000 denier, is stretched in the cold in the ratio of 113.4 and thereupon crimped mechanically in a compression crimping apparatus provided with a closed chamber. The crimped dry tow is then washed with water at 92 C. without tension in the washing device described above until free from lactam.

After drying and cutting, the fibres show the following constants:

Count denier 3.2 Strength of the fibre. when dry g./den 410 Elongation of the dry fibre at break percent 90.3 Initial crimping degree do 19.0

Crimping degree after continuous tensile stress percent; 11.6 Crimp stability do 61.0

Example 2 Count denier 3.3 Strength of the fibre when dry g./den 464 Elongation of the dry fibre at break percent 72.8 Initial crimping degree do 25.6

Crimping degree after continuous tensile stress percent-.. 16.0 Crimp stability do 62.5

We claim: 1. A process for the continuous manufacture of crimped fibres derived from a continuous tow of polymeric e-caprolactam wherein the tow, containing from about 7 to about 14% of monomer and low molecular weight polymer is stretched, subsequently mechanically crimped by compression crimping, washed free of tension in water at temperature of about C. to about (3., dried free of tension, and cut into staples to desired length.

2. A process as claimed in claim 1, wherein the lactamcontaining tow is stretched in several stages at a progressively increasing temperature.

3. A process as claimed in claim 1, wherein the lactamcontaining tow is treated with steam, after stretching and before mechanical crimping.

4. A process as claimed in claim 1 wherein the lactamcontaining tow is washed without tension in water at a temperature of about 80 C. to about 100 C.

References Cited in the file of this patent UNITED STATES PATENTS 2,197,896 Miles Apr. 23, 1940 2,492,574 Heintzelman Dec. 27, 1949 2,575,781 Barach Nov. 20, 1951 2,575,838 Rainard Nov. 20, 1951 2,669,001 Keen Feb. 16, 1954 2,715,309 Rosenstein et al Aug. 16, 1955 2,733,122 Herele et al Jan. 31, 1956 OTHER REFERENCES Article, Twist-Setting and Yarn-Setting of Nylon Yarns, in Rayon Textile Monthly, February, 1945. (Copy in Division 21 in 28-TWS.) 

1. A PROCESS FOR THE CONTINUOUS MANUFACTURE OF CRIMPED FIBRES DERIVED FROM A CONTINUOUS TOW OF POLYMERIC -CAPROLACTAM WHEREIN THE TOW, CONTAINING FROM ABOUT 7 TO ABOUT 14% OF MONOMER AND LOW MOLECULAR WEIGHT POLYMER IS STRETCHED, SUBSEQUENTLY MECHANICALLY CRIMPED BY COMPRESSION CRIMPING, WASHED FREE OF TENSION IN WATER AT TEMPERATURE OF ABOUT 80*C. TO ABOUT 100*C. DRIED FREE OF TENSION, AND CUT IN STAPLES TO DESIRED LENGTH. 